The quick answer is yes.  However, you will not see SSAS as one of the source node types.  Any existing model can be used as a source for another model via a node called Pyramid.  The way it works is to create a Discover report using the SSAS model as the source and then use that report as input to the new model.  The trick is to include all the necessary fields that you want combined to filter the data.

Here is an example:

1. I created a report from an SSAS model.
    
2. I then created a model that uses the report as a source.
    
3.  I combined the data with an Excel file that contains Budget info.
    
4. Finally, I create a new report from the new model.